Pain… prescription… pain… prescription… pain… it is a cycle that plagues those unfortunate enough to understand the vicious reality of chronic pain and the road that often leads to addiction. For Department of Biomedical Sciences Associate Professor, Dr. Shane Hentges, understanding the neural processes that lead to the diminished effectiveness of drug therapies is a critical first step to finding a solution.

Hentges’ research focuses specifically on the receptors that beta-endorphins act on to encode pain relief. Over time, these receptors become desensitized to the effects of opioid drugs in the system, causing the user to require higher dosages to find relief.

“In the end we’ve never found anything better than opioids for managing pain, but there are downfalls,” said Dr. Hentges. “To better treat chronic pain and prevent opioid abuse, it is essential to understand how opioids affect the brain's reward pathways and to determine why opioids become less effective with repeated use.”

Through her research, Dr. Hentges and her colleagues have discovered that in a specific neuron pathway, involving the endorphin-releasing proopiomelanocortin neurons (POMC), it is the location of the opioid receptors within the neurons that determines whether desensitization occurs. The goal is to uncover what underlies the ability of some opioid receptors to resist desensitization. It then may be possible to design drugs that produce less tolerance or have lower potential for abuse.

For the 100 million U.S. adults affected by chronic pain (to the tune of up to $635 billion each year), Hentges’ research is part of a larger effort to understand chronic pain and therapies for people who often feel like their options for a normal life are slim. The National Institutes of Health – who funds Dr. Hentges’ work – has 189 active studies, and 871 open clinical trials related to chronic pain and addiction.

“At the basic level, we need to understand opioid systems in the body – understand the body’s natural pain management tactics versus drug therapies to hopefully find a better way to manage chronic pain,” said Hentges. “I’m not curing pain or addiction, but the way we begin to have options is to really understand how these systems work.”